While running the latest version of Traktor and OS X I noticed that Traktor would freeze when I plugged in the S2.
This might be obvious for some, but I had forgotten that the S2 contains an update utility that updates the firmware on the S2. After updating the firmware all my freezing issues went away!
Do the following to update the firmware on the S2.
Plug in the S2 to your PC using USB. Turn the S2 on by pressing the power button on the back of the S2.
Open the Device Updater using Spotlight (command + spacebar).
The Device Updater will inspect the version of firmware running on the S2 and the latest firmware available for the S2.
Update the firmware and the freezing should be fixed!